The present invention relates generally to the field of rotary cutting dies, and more particularly to an improved method and apparatus for making and using such dies.
Rotary cutting dies have been manufactured and used for numerous years. Conventionally, rotary cutting dies are formed from an opaque, resinous die plate material supporting a metallic cutting rule. The cutting rule extends above the surface of the resin die plate and defines a cutting design. The design created by the metallic cutting rule is employed to cut, score or perforate material, such as paper, cardboard or the like, through the rotary cutting process.
Usually, rotary cutting dies are sized to be mounted either on discrete sections of a rotary cutting machine die cylinder or along the entire surface thereof. To accommodate either type of die, the die cylinder typically contains a number of receiving holes spaced at pre-determined intervals. The receiving holes are positioned in an array along the die cylinder, and are configured to receive screws or other fasteners that extend through the die to affix the die to the die cylinder. Mounting holes are bored into the cutting die to align with the receiving holes in the die cylinder. The rotary cutting die is thus aligned and positioned on the die cylinder to reflect the predetermined pattern for the cutting, scoring or perforating process.
Because the die plate of the rotary cutting die is normally formed from an opaque material, the precise hole placement required to properly mount and align the cutting die on the die cylinder cannot be readily determined and must be obtained by approximation or guess. In an attempt to solve this alignment problem, a guide bar, having guide holes spaced along its longitudinal axis to match the spacing of the receiving holes in the die cylinder, has been used. The guide bar is placed along the top surface of a rotary cutting die while the cutting die is held in place over the die cylinder. The guide bar is extended across the cutting die and the die cylinder to indicate the position of the receiving holes beneath the cutting die provided in the die cylinder. By aligning the guide holes in the guide bar with the receiving holes in the die cylinder, the position of the mounting holes required to be bored or drilled into the cutting die can be more easily determined. Subsequently, the mounting holes are drilled in the cutting die and the cutting die is mounted on the die cylinder, as described above. While the guide bar has produced satisfactory results, inaccuracies in locating the receiving holes still frequently occur.
Inaccurate alignment and positioning of mounting holes may be occasionally remedied by re-drilling or otherwise forming the holes without unduly affecting or jeopardizing the integrity of the cutting die. Often, however, inaccurate mounting hole positioning in the cutting die results in the cutting die being ruined, necessitating a new cutting die being formed. When cutting dies are scrapped, significant overhead costs and down time are incurred. Moreover, inaccurate mounting hole positioning increases production costs and lowers plant productivity.